1. Technical Field
The present invention relates to a display method and a display medium. The present invention particularly relates to a display method and a display medium that are suitable for utilizing for an electronic paper and the like.
2. Related Art
Along with the advancement of computerization in recent years, the amount consumed of paper as a communication medium is continuing to increase. However, as a medium for replacing paper, electronic paper, an image display medium with which recording and deleting an image can be repeated is gathering attention to. In order to put the electronic paper to use in practice, it is required that the electronic paper, as portable, lightweight and not bulky (thin) as paper, requires little energy for rewriting, and has high reliability with little deterioration with repeated rewriting.
Further, although visibility of the electronic paper is required to be similar to that of paper, it has been difficult to realize the electronic paper because there are the following problems in conventional techniques:
(1) liquid crystal method: since a deflecting plate is used therein, light usage efficiency is low and a reflection coefficient is decreased;
(2) twist ball method: due to an imperfect black-and-white hemisphere state, a contrast and a reflection coefficient are hindered; and
(3) electrophoretic method: due to an imperfect change-over of particles of different colors, light leakage between particles, and a specific electrode constitution, a contrast and a reflection coefficient are hindered.
Display technologies that are suitable for use in such a display medium include methods in which display is carried out by depositing and dissolving metals such as silver through application of electric fields or light irradiation utilizing an electrolyte like a silver salt solution, and methods in which display is carried out by utilizing organic photochromic materials such as fulgides.
However, the method utilizing the electrolytic solution is basically for a black-and-white display and, for a color display, it is necessary to use a color filter. Accordingly, there is a problem in that, in a reflection-type display medium, usage efficiency of light comes to be about one third and the display is darkened. Further, in the method using the photochromic material, there is a problem in that a sufficient density of developed color can not be obtained.